The invention relates to improvements in powered airships and more particularly to a powered airship having a flexible soft envelope inflated and pressurized by hot air and capable of directed flights for transporting loads over distances and employing an improved arrangement for controlling the free lift of the airship.
Airships of this type have been referred to as dirigibles and originally referred to as blimps when the airship is nonrigid. The present invention in particular relates to a hot air inflated airship of the nonrigid pressure type. The main envelope or pressure hull is formed of a fabric such as a laminated plastic and Dacron, or of suitable other material which is lightweight, high temperature resistant, extremely strong and impermeable to gas leakage. The envelope of the airship is horizontally elongate and is primarily symmetrical with load lines distributed over the body of the envelope for carrying a payload therebelow. The load lines are also particularly arranged to support hot gas pressure inflation means which preferably will be in the form of one or more propane fueled burners with a fan inflation means. The fan or blower which pressurizes the airship is driven by a suitable motor which may be propane or gasoline fueled. The airship carries a propelling engine and is propeller driven to travel in controlled horizontal flight.
The plastic fabric envelope when not in use can be folded and shipped or stored in the space which takes up less than 1% of its inflated volume. The envelope can be relatively rapidly inflated by the operation of the fan and the free lift is controllable by control of the burner which controls the temperature of the air within the envelope. The direction of flight is controlled by tail fins at the aft end of the airship envelope. These tail surfaces preferably include a rigid or stable portion which stabilizes the airship in horizontal flight, and a manipulable portion which changes the direction of flight. Vertically extending control surfaces are pivoted to the left or right to change the direction of flight, and horizontally extending surfaces move up or down to cause the airship to ascend or descend. Primarily, the temperature of the hot air within the airship is controlled to provide sufficient lift for the weight of the envelope and the payload being carried so that essentially free lift is present while the airship is in flight, and it ascends or descends in accordance with the change in angle of the control tail surfaces.
The envelope is maintained under superpressure by a constantly operated fan driven by an engine, and the fan is supported on the gondola and blows air upwardly past a controlled burner system which is uniquely regulated to regulate the temperature of the air within the envelope. This air temperature is important inasmuch as it determines the free lift of the airship for carrying the payload. The gondola which carries the pilot and the controls and which also supports the inflation mechanism as well as the engine for driving the fan for moving the structure horizontally is supported on cables which extend downwardly from the top of the envelope through the hollow hull to be attached to the top of the gondola. In accordance with the features of the present invention, a thermocouple is supported on one of the cables preferably directly above the inflation fan and burner, but a substantial distance thereabove, and also the thermocouple is spaced from the wall of the envelope so that temperatures outside of the envelope do not have a direct effect on its reading. The thermocouple sends a signal down to a control box accessible to the pilot within the gondola, and the control box is wired to regulate and control a valve supplying the burner. In flight the operator, who knows the amount of payload carried by the airship sets the temperature within the airship accordingly so that the correct free lift will be maintained for supporting the airship in level flight.
Accordingly, it is an object of the present invention to provide an improved inflatable hot air airship which is capable of closely regulated lift by controlling the temperature within the airship hull.
A further object of the invention is to provide an improved burner control arrangement for a hot air airship which obviates difficulties heretofore encountered in other airships.
A still further object of the invention is to provide a unique and improved hot air supply control for a thermal airship which is capable of maintaining the free lift in the airship for normal flight and which is capable of supplying additional free lift for emergency conditions and which provides safety factors not heretofore available.
Other objects, advantages and features will become more apparent as will equivalent structures which are intended to be covered herein, with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiment in the specification, claims and drawing, in which: